Battery Drain?

I have a 91 prelude 5 speed, The battery keeps going dead! I disconnected the positive lead and the battery holds it charge. With the engine running there is 14.5 volts charging the batery. If I disconnect the battery and check for a amperage draw there is a .03 amp drain. I thought maybe the alternator was the problem so I disconnected the main positive lead off the alternator. That made no differance. Any suggestions?

Reply to
boatsrfun
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There are a LOT of things on cars today that stay on even when ignition is off. These are supposed to be very low drain, and battery should last for a week or two between use. If storing a car for a long time, yeah, then they recommend removing battery lead.

What usually happens is that one of those systems left connected has gone bad, and now represents a high drain. Are any accessories not working? That might be suspect. Radio is one system that stays connected so memory can remember station presets and last selected station. Engine control computer is another. If you have a seperate digital clock (not part of radio) that stays connected. I believe on many cars power is left on to the headlight relay, relying on lack of control signal to keep relay off when power off. But a bad relay can draw current (I've had that one happen).

I wish auto and radio mfgs would go to flash memory so they would not need battery power to keep these "memories" alive.

Reply to
Don Stauffer in Minnesota

Exactly, Don.

Now, if he is only drawing 30 milliamperes, that is not much and the battery should last for a good while. He is apparently not getting this kind of charge life, and I can appreciate it because I have the same problem on my Reatta.

What is happening, in my case, is that intermittently some other system comes on and the drain goes from 0.03-0.04 amperes up to a much higher number, several amps likely, running the battery down. When I go back to check it, the car may well be drawing the low figures again.

These faults are hard to find, sometimes. I have bought a VOM which will record the maximum current drain, and had planned to go down the schematic, removing branches until I find the culprit.

Now, I think my wife may have found the culprit without all that. In the middle of the night a few days ago, she woke up and saw the tail lights go on. This was a lucky observation for me.

Our OP may have to trace this thing out the hard way.

Reply to
hls

I always pull one of the battery (I think it's the positive one) cables off when I park my 1978 Dodge van in my driveway.I have an old battery cable tied in there.I always let it drape out of there. cuhulin

Reply to
cuhulin

I have a couple of battery disconnects that I use in my cars. They are relatively cheap, at WalMart.

Still, there is nothing like having a car that works the way is it supposed to.

Reply to
hls

30 mA is not much draw. If you are SURE about that number, change the battery.

--scott

Reply to
Scott Dorsey

wrote: (91 prelude 5 speed)

The battery keeps going dead.

__ If I disconnect the positive cable the battery holds its charge. So the battery is okay - the drain is not internal.

__ With the engine running there is 14.5 volts charging the battery. So the alternator voltage regulation is okay - it is normal.

__ Disconnecting the main positive alternator lead makes no difference. So the alternator diodes are not the source of the drain.

__ If I disconnect the battery there is a .03 amp drain. Thirty milliamps to run clocks and memory chips is not much. .03 amps x 24 Hours = 0.72 Ampere-hours, not enough to drain a car battery in one day.

__ Any suggestions? Post again with more information, including how you measure amperage drain with the battery disconnected.

Good luck.

Rodan.

Reply to
Rodan

If you disconnect the battery, how is there a 0.03 amp drain?

How much of a drain is there with the battery installed? Is the battery clean? Could there be acid/crud from the positive terminal to a nearby ground?

Reply to
AZ Nomad

Use a spoonful or two of baking soda in a cup of warm water and a rag or a few paper napkins and clean the battey off real good, then flush the battery off with fresh water.That should clean the crud off. cuhulin

Reply to
cuhulin

I read his post to mean that he removed a cable and put the ammeter in series. Maybe I was wrong. If he just disconnected the battery, he couldn't have measured any drain. A drain via surface electrolyte is not measurable that way.

To me, it all still points to some other system being activated, intermittently, that runs his battery down.

I had a Buick that nearly drove me crazy with this. Every morning the battery was dead, or nearly so. After trying all the simple things, I finally caught this car "in delicto flagrante": the seat belt retractors started activating while the car was off and parked, and that was enough to run down the battery overnight. Very intermittent.

My Reatta also runs down (usually showing 30 - 40 ma parasitic drain), but I dont drive this car much and I havent spent the time to dig into this electronic nightmare.

Reply to
hls

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